Hot plate precipitation measuring system

ABSTRACT

A precipitation measuring system comprising a top thermal plate positioned to maximize exposure to falling precipitation and includes at least one ridge circumscribing the top surface for capturing precipitation. A second thermal plate is positioned under the top thermal plate to protect it from falling precipitation while still exposing it to the same atmospheric temperature and wind conditions. At least one solar radiation sensor is connected to the precipitation measuring system to measure solar radiation contacting at least one of the top and bottom thermal plates. During a precipitation event, the top and bottom thermal plates are maintained at a constant temperature and a power consumption curve for each thermal plate is quantified. The precipitation rate is measured by the difference in the power consumption curve for the top thermal plate and the power consumption curve for the bottom thermal plate.

RELATED INFORMATION

This patent application is a continuation of patent application Ser. No.09/395,088 filed Sep. 13, 1999 now U.S. Pat. No. 6,546,353, which ishereby incorporated by reference into this patent application.

GOVERNMENT FUNDED INVENTION

The invention was made with Government support under Agreement No.DTFA01-98-C-00031 awarded by the Federal Aviation Administration. TheGovernment has certain rights in this invention.

FIELD OF THE INVENTION

The invention relates to meteorological instrumentation, andparticularly to an improved method and apparatus for real-time detectionand quantification of precipitation reaching the earth's surface at agiven point.

Problem

Rain gauges and snow gauges are common names for devices designed toquantify precipitation and the winter equivalent of precipitation thatreaches the earth's surface. Various types of rain and snow gauges havebeen developed to detect and quantify precipitation and its winterequivalent. One example of a precipitation gauge uses a container tocollect free falling precipitation for later measurement. In the case ofwinter precipitation or snow, the snow is collected in a containerhousing chemicals to melt the snow into a liquid form. In anotherexample of a precipitation gauge, the rain or snow is collected in acontainer and upon accumulation of a measurable amount, the gaugedetects or “tips” under the weight of the melted snow pouring the liquidinto a collection container. The weight of the collected sample isconverted into a corresponding depth measurement to estimate the totalaccumulation of precipitation and the precipitation rate over time. Inboth examples, the precipitation ideally free-falls into theaccumulation container at the same rate and in the same quantity as theprecipitation would fall in the immediate vicinity of the gauge.

One problem with these gauges, however, is the overall accuracy of thegauge is limited to mechanical resolutions of accumulation. Therefore, alight snowfall or rainfall event can go completely undetected due toevaporation from the gauge before detection or a measurable amount ofaccumulation occurs. Another related problem with these gauges is theinability to report real-time accumulation. Even during heavyprecipitation events, there is a time delay ranging from a few minutesto thirty minutes or more before a measurable sample amount iscollected.

To correct these problems, more recent gauges such as the gaugedescribed in U.S. Pat. No. 5,744,711 have been developed to providereal-time detection and measurement of precipitation events. Thesegauges use a pair of thermal plates housed in a cylindrical tube. Afirst thermal plate or sensor plate is horizontally positioned in thetube to collect precipitation. A second thermal plate or reference plateis vertically positioned under the first thermal plate to protect itfrom contact with the precipitation while still allowing exposure to thesame atmospheric temperature conditions. The pair of thermal plates areindividually heated and maintained at a substantially constanttemperature during a precipitation event. The difference in current usedto maintain the individual thermal plates at the substantially constanttemperature is quantified and converted into the precipitation rate. Afan positioned in the tube under the thermal plates draws air throughthe tube to prevent a convecting heat plume from developing at the topof the tube.

A first problem with this gauge is inaccuracies in data collectioncaused by solar radiation. During periods when precipitation is notfalling, solar radiation contacting the top thermal plate heats theplate causing the power required to maintain the substantially constanttemperature to fluctuate. These power fluctuations cause noise and otherinaccuracies in measuring precipitation events.

A second problem with this gauge is capturing the precipitation andpreventing it from sliding off the top thermal plate before the meltingand evaporation can occur that causes the power fluctuation. This isespecially critical during blowing precipitation events where the windcarries the precipitation into the system at an angle.

A third problem with the gauge is that it is large and bulky requiringdedicated mechanical components such as a fan, fan motor and tube, whichincrease cost and require frequent maintenance. Furthermore, duringprecipitation measuring in remote locations, it is desired to carry aslittle equipment as possible. This is especially true in locationsaccessible only by helicopter or all terrain vehicles.

A fourth problem with the gauge is the inability to differentiatebetween a blowing precipitation event and a natural precipitation event.A blowing precipitation event is where the precipitation, such as snow,has already fallen to the earth's surface, but due to windy or gustyatmospheric conditions is being blown about to different locations. Anatural precipitation event is where the precipitation is falling to theearth's surface for the first time. A natural precipitation event mayoccur in substantially still or windy atmospheric conditions.

For these reasons, it is desirable to have a precipitation measuringsystem that accounts for solar radiation, differentiates betweendifferent precipitation events, is compact, and prevents precipitationfrom leaving the system before melting and evaporation can occur.

Solution

The precipitation measuring system of the present invention overcomesthe problems outlined above and advances the art by providing a hotplate precipitation measuring system that accounts for solar radiation,differentiates between blowing and natural precipitation events, andprevents precipitation from leaving the system before melting andevaporation can occur. In the context of this application, precipitationincludes year round precipitation during both winter and summer months.Some examples of precipitation include without limitation, snow, rain,mist, drizzle, fog, freezing rain, freezing drizzle, sleet, and hail.The precipitation can be blowing precipitation, natural precipitation,or a combination of a blowing and natural precipitation.

The precipitation measuring system comprises a top thermal plategenerally positioned horizontal to maximize exposure to fallingprecipitation and includes at least one ridge circumscribing the topsurface for capturing precipitation. A bottom thermal plate ispositioned directly under the top thermal plate to protect the bottomthermal plate from falling precipitation while still exposing it to thesame atmospheric temperature and wind conditions as the top thermalplate. At least one solar radiation sensor is connected proximate theprecipitation measuring system to measure both direct and scatteredsolar radiation. During a precipitation event, the top and bottomthermal plates are maintained at a constant temperature and a powerconsumption curve for each thermal plate is quantified. The powerconsumption curves are corrected for heating caused by solar radiationand the precipitation rate is measured by the difference in thecorrected power consumption curves for the top and bottom thermalplates.

In another embodiment of the precipitation measuring system the at leastone solar radiation sensor is replaced by a precipitation on/off sensorthat automatically starts the precipitation measuring system at thebeginning of a precipitation event and automatically shuts down thesystem at the end of the event. In yet another embodiment, at least oneother pair of thermal plates is used to determine the occurrence of ablowing precipitation event and a natural precipitation event bymeasuring the difference in the amount of precipitation contacting thepairs of thermal plates.

One or more of the following features can also be incorporated into thepresent precipitation measuring system: 1) a stand, balloon or otherair-borne device to elevate the precipitation measuring system above theearth's surface; 2) a de-icing apparatus to prevent ice from forming onthe stand and other components; and 3) real-time adjustment of thesubstantially constant temperature of the thermal plates to accommodatevarying precipitation rates.

A first advantage of the present invention is that the operatingtemperature of the present precipitation measuring system is lower thanprior art systems because precipitation is captured and trapped by thetop thermal plate. This results in cost savings and reduces the hazardsof working with a heated device. A second advantage of the presentinvention is that it is compact and does not include bulky mechanicalcomponents that wear out or are subject to frequent maintenance. A thirdadvantage of the present invention is that de-icing the stand and othercomponents permits increased accuracy in precipitation measurement. Afourth advantage of the present invention is that the real-timetemperature adjustment of the thermal plates results in power savings,increased accuracy in precipitation measurement, and preventsoverloading during heavy precipitation events.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, illustrates a precipitation measuring system of the presentinvention;

FIG. 2, illustrates a perspective view of a thermal plate of the presentinvention;

FIG. 3, illustrates an alternative embodiment of a precipitationmeasuring system of the present invention;

FIG. 4 illustrates an alternative embodiment of a precipitationmeasuring system of the present invention;

FIG. 5 illustrates the operational steps of a precipitation measuringsystem of the present invention in flow diagram form;

FIG. 6 illustrates alternative operational steps of a precipitationmeasuring system of the present invention in flow diagram form;

FIG. 7 illustrates alternative operational steps for a precipitationmeasuring systems of the present invention in a flow diagram form;

FIG. 8 illustrates control electronics for a precipitation measuringsystem of the present invention in block diagram form; and

FIG. 9 illustrates various applications including ground based andair-borne applications of a precipitation measuring system of thepresent invention.

DETAILED DESCRIPTION

Precipitation Measuring System FIGS. 1-4

FIG. 1 illustrates a perspective view of a hot plate precipitationmeasuring system 100. The major components of precipitation measuringsystem 100 are sensor electronics and stand 112. Sensor electronicsinclude top thermal plate 101, bottom thermal plate 102, sensor controls109, solar radiation sensors 114 and 118, atmospheric temperature sensor115 and remote processor 110. Thermal plates 101 and 102 connect tomounting posts 105 and 106 by brackets 107 and 108. Top thermal plate101 is generally positioned horizontally relative to the earth's surface121 to permit maximum exposure to falling precipitation. In some caseshowever, such as measurement on an inclined surface, top thermal plate101 could be positioned other than horizontal to maximize exposure tofalling precipitation 117. Bottom thermal plate 102 is positioned in afacial relationship directly under top thermal plate 101 to subjectbottom thermal plate 102 to the same ambient temperature and/or airflowwhile facilitating a maximum protection from falling precipitation.Insulation 111 is positioned between top thermal plate 101 and bottomthermal plate 102 to prevent heat generated by one of thermal plates 101and 102 from affecting the other one of thermal plates 101 and 102.

Solar radiation sensor 114 is connected on the top of mounting post 106by bracket 107 to detect solar radiation contacting top thermal plate101. Solar radiation sensor 118 is connected to mounting post 106 at alower elevation than bottom thermal plate 102 to detect solar radiationcontacting exposed surface 119 of bottom thermal plate 102. Thoseskilled in the art will readily understand that solar radiationcontacting bottom thermal plate 102 is generally caused by reflectionoff of ground 121, and thus, solar radiation sensor 118 may not beneeded in some applications where significant reflection does not occur.In alternative embodiments, solar radiation sensor 114 could be locatedat other locations provided it is proximate top surface 116 of topthermal plate 101 to facilitate measuring solar radiation contacting topsurface 116. Similarly, solar radiation sensor 118 could be located atother locations provided it is proximate the exposed surface 119 ofbottom thermal plate 102. Atmospheric temperature sensor 115 isconnected to mounting post 105 proximate bottom thermal plate 102.Alternatively, atmospheric temperature sensor 115 could be connected atother locations on precipitation measuring system 100 so long as it isproximate enough to precipitation measuring system 100 to facilitate anaccurate atmospheric temperature measurement and provided that it doesnot obstruct precipitation 117 from contacting top thermal plate 101.

Sensor controls 109 include processing electronics that control thetemperature of thermal plates 101 and 102. Sensor controls 109 areconnected to bottom thermal plate 102, top thermal plate 101, solarradiation sensors 114 and 118, and atmospheric temperature sensor 115.Sensor controls are also connected to remote processor 110 bycommunications link 113. Alternative sensor control locations includewithout limitation, positioned internal to post 103, operativelyconnected to precipitation measuring system 100 from a remote location,or any location within or proximate to precipitation measuring system100, provided the position does not obstruct precipitation 117 fromcontacting top thermal plate 101. Those skilled in the art will readilyunderstand that sensor controls 109 are calibrated according to the typeof precipitation being measured. For example, the calibration of sensorcontrols 109 could differ when precipitation 117 is summer precipitationand when precipitation 117 is winter precipitation.

Remote processor 110 collects data from top thermal plate 101 and bottomthermal plate 102 for real-time or subsequent precipitation ratecalculation and processing. Remote processor 110 could also be connectedto a plurality of precipitation measuring systems 100. In this caseremote processor 110 collects data from the multiple precipitationmeasuring systems for real-time or subsequent precipitation ratecalculation and processing.

Stand 112 permits elevating top thermal plate 101 and bottom thermalplate 102 above the earth's surface 121. Stand 112 includes a post 103,a base plate 104, and mounting posts 105 and 106. Mounting posts 105 and106 are connected perpendicular to base plate 104. Base plate 104 isconnected to the top of post 103, which is mounted on the earth'ssurface 121. Stand 112 could be various heights above the earth'ssurface as a matter of design choice to accommodate differentapplications of precipitation measuring system 100. For example inmountainous regions or areas with heavy annual snowfall, post 103 wouldbe taller to prevent precipitation measuring system 100 from beingburied in deep snow. Similarly, in areas containing dense vegetationand/or foliage, post 103 could be taller so that thermal plates 101 and102 extend above the vegetation and/or foliage to facilitate capturing amaximum amount of precipitation 117. Likewise, in barren locations, post103 could be shorter to accommodate the lack of vegetation or otherobstructions. In another example, post 103 could be removed fromprecipitation measuring system 100 altogether to improve mobility ofprecipitation measuring system 100.

A preferred feature of the present precipitation measuring system isthat wind speed can be calculated using the bottom thermal plate, whichis not exposed to precipitation but is exposed to the same amount ofwind. The wind speed is calculated by the amount of power consumption inthe bottom thermal plate 102 relative to the atmospheric temperature atprecipitation measuring system 100.

In alternative embodiments designed for severe winter weatherconditions, precipitation measuring system 100 also includes a de-icingapparatus to de-ice stand 112 and solar radiation sensors 114 and 118.Specifically, during severe winter weather conditions, ice forms onmounting posts 105 and 106, brackets 107 and 108, base plate 104 andsolar radiation sensors 114 and 118. The ice affects the power requiredto maintain thermal plates 101 and 102 at a constant temperature,affects solar radiation measurement, and as will be apparent from thefollowing discussion affects the accuracy of precipitation measuringsystem 100. The de-icing apparatus could be any apparatus that preventsice from forming on mounting posts 105 and 106, brackets 107 and 108,base plate 104, and solar radiation sensors 114 and 118. Examples of thede-icing apparatus include without limitation, the application ofchemical anti-freezes or an electrode or other heating element thatslightly heats mounting posts 105 and 106, brackets 107 and 108, baseplate 104, and solar radiation sensors 114 and 118.

FIG. 2 illustrates an example of top thermal plate 101. Top thermalplate 101 includes concentric ridges 200, 201, and 202 circumscribingtop surface 116 to catch and retain precipitation 117 on top thermalplate 101. The concentric ridges are designed to prevent precipitation117 from sliding off of top thermal plate 101 before melting and/orevaporation occurs, making precipitation measuring system 100 highlysensitive to light precipitation events that are at or about 0.01 inchesper hour of accumulation. Alternative configurations for top thermalplate 101, include without limitation, a single concentric ridgecircumscribing the diameter of top surface 116 or a plurality ofconcentric ridges so as to form a ribbed top surface 116.

Bottom thermal plate 102 should be identical to top thermal plate 101 sothat top and bottom thermal plates 101 and 102 cool in a linearrelationship relative to each other. This facilitates precipitationmeasuring and wind speed calculation by eliminating additionalcalculations to compensate for non-linear cooling relationships causedby different geometrically shaped thermal plates. In alternativeembodiments, top and bottom thermal plates 101 and 102 could comprisevarious shapes of different geometry as a matter of design choice,provided top thermal plate 101 and bottom thermal plate 102 areidentical to facilitate the linear cooling relationship. In onepreferred embodiment, top and bottom thermal plates 101 and 102 arecircular in shape and are 6 inches in diameter. Top and bottom thermalplates 101 and 102 could be constructed from any conductive material,one example being aluminum.

FIG. 3 illustrates another embodiment of a hot plate precipitationmeasuring system of the present invention, namely precipitationmeasuring system 300. Precipitation measuring system 300 is identical inall respects to precipitation measuring system 100 except that inprecipitation measuring system 300 solar radiation sensors 114 and 118is replaced by a precipitation on/off sensor 301. Precipitation on/offsensor 301 lowers the noise threshold in precipitation measuring system300 by sensing the beginning of a precipitation event and startingprecipitation measuring system 300. Precipitation on/off sensor 301 thensenses the end of the precipitation event and turns precipitationmeasuring system 300 off. Precipitation on/off sensor 301 could turnprecipitation measuring system 300 off immediately following theprecipitation event or could turn precipitation measuring system 300 offat a predetermined time following the end of the precipitation event.Advantageously, turning precipitation measuring system 300 off at apredetermined time following the precipitation event helps ensure theprecipitation event has ended. This prevents missing part of anintermittent precipitation event because of system warm up. Thus,precipitation measuring system 300 is only active during actualprecipitation events, eliminating false readings due to solar radiationand/or wind. A preferred feature of this embodiment is thatprecipitation on/off sensor 301 reduces the power consumption ofprecipitation measuring system 300 by turning precipitation measuringsystem 300 on only during precipitation events, and turningprecipitation measuring system 300 off at the termination of theprecipitation event.

FIG. 4 illustrates another embodiment of a hot plate precipitationmeasuring system of the present invention, namely precipitationmeasuring system 400. Those skilled in the art will recognize numerousother configurations that are applicable to the invention describedabove. Those skilled in the art will also appreciate how combinations offeatures described below can be combined with the above-describedembodiment.

Precipitation measuring system 400 includes precipitation measuringsystem 100 and a second precipitation measuring system 411 connected topost 103 by arm 404. Alternatively, precipitation measuring system 411could be connected to post 103 by any suitable manner or be mounted onits own post e.g. 103 provided that it remains exposed to precipitation117. Second precipitation measuring system 411 includes a second topthermal plate 401, a second bottom thermal plate 402, brackets 408 and409, mounting posts 406 and 407, solar radiation sensor 410 and baseplate 405. Thermal plates 401 and 402, base plate 405, mounting posts406 and 407, solar radiation sensor 410, and brackets 408 and 409 areidentical in all respects to thermal plates 101 and 102, base plate 104,mounting posts 105 and 106, solar radiation sensor 114, and brackets 107and 108 respectively.

Precipitation measuring system 400 includes the same functionalcapabilities as precipitation measuring system 100, but includes theadded capability of determining a blowing precipitation event from anatural precipitation event. An important aspect of this embodiment isthe elevation difference between precipitation measuring systems 100 and411. One of precipitation measuring systems 100 and 411 should be placedsubstantially higher than the other one of precipitation measuringsystems 100 and 411 so that it is above precipitation that has alreadyfallen but is being blown about by windy atmospheric conditions. Thispermits only natural falling precipitation to contact the higher one ofprecipitation measuring systems 100 and 411. The other one ofprecipitation measuring systems 100 and 411 should be placed at a lowerelevation to permit both natural falling precipitation and precipitationthat has already fallen but is being blown about by windy atmosphericconditions to contact the lower one of precipitation measuring systems100 and 411. Using this configuration, differentiation between a blowingprecipitation event and natural precipitation event can be made by acomparison of precipitation 117 measured at the individual precipitationmeasuring systems 100 and 411. If both precipitation measuring systems100 and 411 measure substantially the same amount of precipitation, thenit is known that the precipitation event is a natural precipitationevent only. If no precipitation is detected on the higher one ofprecipitation measuring systems 100 and 411 then it is known that theprecipitation event is a blowing precipitation event only. Ifprecipitation is detected on both of precipitation measuring systems 100and 411, but significantly more precipitation is measured on the lowerone of precipitation measuring systems 100 and 411, then it is knownthat the precipitation event is a combined natural and blowingprecipitation event.

Those skilled in the art will appreciate that numerous combinations ofelevation differences for precipitation measuring systems 100 and 411exist as a matter of design choice. Some examples of elevations includewithout limitation, placing precipitation measuring system 100 at anelevation of 100 feet relative to the earth's surface 121, and placingprecipitation measuring system 411 at an elevation of 30 feet relativeto the earth's surface 121. In another example, precipitation measuringsystem 100 could be located at an elevation of 50 feet relative to theearth's surface 121, while precipitation measuring system 411 could belocated at an elevation of 5 feet relative to the earth's surface 121.

It should also be noted that precipitation measuring system 100 could bereplaced by precipitation measuring system 300, which includesprecipitation on/off sensor 301. In this case, precipitation measuringsystem 411 could include solar radiation sensors 114 and 118 or aprecipitation on/off sensor e.g. 301. Solar radiation sensors 114 and118 and precipitation on/off sensor e.g. 301 are not required, however,as precipitation on/off sensor 301 on precipitation measuring system 300could be used to power down the entire precipitation measuring system400.

In other embodiments, a plurality of precipitation measuring systems 411could be connected to post 103 to improve measurement accuracy.Similarly, a plurality of precipitation measuring systems 400 could beemployed at a plurality of locations and could include their own sensorcontrols and remote processors or be connected to sensor controls 109and remote processor 110. Multiple precipitation measuring systems e.g.411 or 400 improve the accuracy of measuring precipitation rates,detecting blowing and natural precipitation events, and calculating windspeed, as multiple sets of data is collected.

Operational Steps and Control—FIGS. 5-8

FIG. 5 illustrates the operational steps of a precipitation measuringsystem in a flow diagram form. The system begins at step 500 andproceeds to system initialization at step 502. System initialization 502includes, but is not limited to, heating top thermal plate 101 andbottom thermal plate 102 to a predetermined operating temperature, andcalibrating top thermal plate 101 with bottom thermal plate 102. Theoptimal operating temperature for top thermal plate 101 is generallybelow the local boiling point of water, yet hot enough to evaporateprecipitation 117 substantially instantaneously, where substantiallyinstantaneously can be as much as 5-10 seconds. Alternatively, theoperating temperature could be above the local boiling point of water insome cases, such as during heavy precipitation events. The operatingtemperature is programmable and adjustable depending on criticaloperating conditions that include without limitation, precipitationrate, ambient temperature, humidity, and precipitation size. Forexample, small precipitation sizes evaporate more quickly than largeprecipitation sizes falling at the same rate so that operatingtemperatures can be lower for small precipitation sizes.

When top thermal plate 101 and bottom thermal plate 102 are at anoptimal operating temperature for present conditions, a continuous cyclebegins for both thermal plates 101 and 102. The temperature of topthermal plate 101 is tested at step 504. If the temperature is above orbelow an ideal predetermined temperature setting at decision step 505the current to top thermal plate 101 is adjusted accordingly at step 506to maintain the ideal predetermined temperature and processing continuesat step 512. If the temperature is at the ideal predetermined setting atdecision step 505 then processing continues at step 512.

Substantially concurrently with the continuous process of steps 504,505, and 506, the temperature of the bottom thermal plate 102 is testedat step 509. If the temperature is above or below the idealpredetermined temperature setting at decision step 510 the current tobottom thermal plate 102 is adjusted accordingly at step 511 to maintainthe ideal predetermined temperature and processing continues at step512. If the temperature is at the ideal predetermined setting atdecision step 510 then processing continues at step 512.

Substantially concurrently with the continuous process of steps 504,505, 506, 509, 510 and 511 the atmospheric temperature is measured atstep 507 and the solar radiation contacting top thermal plate 101 andbottom thermal plate 102 is measured at step 517. The atmospherictemperature and solar radiation are recorded with a time stamp in sensorcontrols 109 at step 508. One skilled in the art will appreciate thatthe atmospheric temperature could be tested at step 507 and recorded atstep 508 on a continuous basis or at predetermined time intervals duringprocess steps 504, 505, 506, 509, 510 and 511 as a matter of designchoice. One skilled in the art will also appreciate that the steps ofcontrolling temperature by controlling current to the bottom thermalplate 102 and top thermal plate 101 could alternatively be bycontrolling voltage so that a constant power setting is achieved forbottom thermal plate 102 and and/or top thermal plate 101.

Substantially concurrently with the continuous thermal plate temperaturetesting process and atmospheric temperature testing process, the amountof current drawn by top thermal plate 101 and bottom thermal plate 102are compared at step 512. As precipitation 117 strikes top thermal plate101, precipitation 117 substantially instantaneously melts or evaporatesthereby cooling top surface 116 of top thermal plate 101. Bottom thermalplate 102 is exposed to the same ambient environmental conditions as topthermal plate 101 except for contact with precipitation 117. Thus, inthe absence of solar radiation, the difference in the power consumptionof top thermal plate 101 versus the power consumption of bottom thermalplate 102 is directly proportional to the rate of precipitation 117falling on top thermal plate 101. Further, since the individual meltingor evaporating particles of precipitation 117 have a different powerconsumption curve depending on the type of precipitation 117, forexample, snow, drizzle or rain, the different types of precipitation 117can be distinguished by comparing the respective power consumptioncurves.

The power consumption for top thermal plate 101, bottom thermal plate102, and the difference in power consumption are recorded and timestamped in sensor controls 109 at step 513. At step 514, remoteprocessor 110 periodically polls the local processor in sensor controls109 to retrieve the precipitation data, atmospheric temperature data andsolar radiation data for further processing and recording along with thedata from other precipitation measuring systems.

If the power consumption sensing and data recording are to continue atdecision step 515, processing continues at step 512. If the powerconsumption sensing and data recording are not to continue at decisionstep 515, then processing ends at step 516.

FIG. 6 illustrates alternative operation steps of a precipitationmeasuring system in a flow diagram form. The system begins at decisionstep 600 with precipitation on/off sensor 301 sensing for aprecipitation event. If a precipitation event is not detected at step600, precipitation on/off sensor waits at step 604 and continues sensingfor an event step 600. If a precipitation event is detected at step 600,precipitation on/off sensor in cooperation with the processor in sensorcontrols 109 starts precipitation measuring system 100 and proceeds tosystem initialization at step 602. System initialization 602 includes,but is not limited to, heating top thermal plate 101 and bottom thermalplate 102 to a predetermined operating temperature, and calibrating topthermal plate 101 with bottom thermal plate 102.

When top thermal plate 101 and bottom thermal plate 102 are at anoptimal operating temperature for present conditions, a continuous cyclebegins for both thermal plates 101 and 102. The temperature of topthermal plate 101 is tested at step 605. If the temperature is above orbelow an ideal predetermined temperature setting at decision step 606the current to top thermal plate 101 is adjusted accordingly at step 607to maintain the ideal predetermined temperature and processing continuesat step 611. If the temperature is at the ideal predetermined setting atdecision step 606 then processing continues at step 611.

Substantially concurrently with the continuous process of steps 605,606, and 607, the temperature of bottom thermal plate 102 is tested atstep 608. If the temperature is above or below the ideal predeterminedtemperature setting at decision step 609 the current to bottom thermalplate 102 is adjusted accordingly at step 610 to maintain the idealpredetermined temperature and processing continues at step 611. If thetemperature is at the ideal predetermined setting at decision step 609then processing continues at step 611. Substantially concurrently withthe continuous process of steps 605, 606, 607, 608, 609 and 610 theatmospheric temperature is measured at step 616 and recorded with a timestamp in sensor controls 109 at step 617.

Substantially concurrently with the continuous thermal plate temperaturetesting process and atmospheric temperature testing process, the amountof current drawn by top thermal plate 101 and bottom thermal plate 102are compared at step 611. As precipitation 117 strikes top thermal plate101, the power consumption of top thermal plate 101, bottom thermalplate 102, and the difference in power consumption is recorded with andtime stamped in sensor controls 109 at step 612. At step 613, remoteprocessor 110 periodically polls the local processor in sensor controls109 to retrieve the precipitation data and atmospheric temperature datafor further processing and recording along with the data from otherprecipitation measuring systems.

If the precipitation event is still in progress at step 614 processingcontinues at step 611. If the precipitation event has ended at step 614,on/off sensor 301 in cooperation with the microprocessor in sensorcontrols 109 shuts down the precipitation measuring system andprocessing ends at step 615. Advantageously, in this embodiment thenoise from solar radiation is substantially eliminated because theprecipitation measuring system is only activated during a precipitationevent.

FIG. 7 illustrates alternative operational steps for the precipitationmeasuring systems of FIG. 5 in a flow diagram form. The system begins atstep 500 and proceeds through steps 502-511 at step 701. Substantiallyconcurrently with the continuous thermal plate temperature testingprocess and atmospheric temperature testing process, the amount ofcurrent drawn by top thermal plate 101 and bottom thermal plate 102 arecompared at step 702. The power consumption for top thermal plate 101,bottom thermal plate 102, and the difference in power consumption arerecorded with a time stamp in sensor controls 109 at step 703. At step704, remote processor 110 periodically polls the local processor insensor controls 109 to retrieve the precipitation data, atmospherictemperature data and solar radiation data for further processing andrecording along with the data from other precipitation measuringsystems. If the power consumption sensing and data recording are tocontinue at decision step 707, processing continues at decision step707. If the precipitation rate has increased at decision step 707 thenthe substantially constant temperature of thermal plates 101 and 102 isincreased to accommodate the increase in the precipitation rate at step708. If the precipitation rate has decreased at decision step 707 thenthe substantially constant temperature of thermal plates 101 and 102 isdecreased to accommodate the decrease in the precipitation rate at step708. If the precipitation rate has not increased or decreased atdecision step 707 then processing continues at step 702. If the powerconsumption sensing and data recording are not to continue at decisionstep 706, then processing ends at step 705.

A preferred feature of this embodiment is the real-time control of powerto thermal plates 101 and 102. Advantageously the real-time control ofpower to thermal plates 101 and 102 permits increased accuracy inprecipitation measuring by adjusting the substantially constanttemperature to accommodate different precipitation rates. Alsoadvantageously, the real-time control of power saves power by reducingpower during lighter precipitation events.

FIG. 8 illustrates control electronics for the precipitation measuringsystem in block diagram form. The precipitation measuring system ispowered by 110 V AC or in the alternative by 12 V DC for remoteoperations. In either case the voltage source 800 with appropriategrounding 801, provides power for the entire system.

Top thermal plate 101 is connected in a loop with thermistor 802 to testtemperature, and amp controller 803 to adjust the current to top thermalplate 101 as needed. Alternatively, temperature of top thermal plate 101could be measured by sensing a measure of resistance of the heatingelement in top thermal plate. Microprocessor 804 compares and timestamps the data on current draw by top thermal plate 101 and transmitsthe data to a remote processor 805 for final precipitation ratecalculations. Similarly, bottom thermal plate 102 is connected in a loopwith thermistor 806 to test temperature, and amp controller 807 toadjust the current to bottom thermal plate 102 as needed. Microprocessor804 compares and time stamps the data on current draw by bottom thermalplate 102, and transmits the data to remote processor 805 for finalprecipitation rate calculations. Temperature sensor 810 is connected tomicroprocessor 804. Microprocessor 804 monitors temperature sensor 810and time stamps the data on atmospheric temperature and transmits thedata to remote processor 805 for calculation of wind speed.

In embodiments that include solar radiation sensors, solar radiationsensors 808 are connected to microprocessor 804. Microprocessor 804compares and time stamps the data on solar radiation, and transmits thedata to remote processor 805 for adjustment of the precipitation data toaccount for solar radiation and final precipitation rate calculations.

In embodiments that include a precipitation on/off sensor, precipitationon/off sensor 809 is connected to microprocessor 804. Microprocessor 804monitors precipitation on/off sensor 809 for the beginning of aprecipitation event and starts the precipitation measuring system at thebeginning of the precipitation event. Microprocessor 804 then monitorsprecipitation on/off sensor 809 for the end of a precipitation event andshuts down the precipitation measuring system at the end of theprecipitation event.

Applications' FIG. 9

FIG. 9 depicts ground based and air-borne settings for a hot plateprecipitation measuring system 900 of the present invention. Duringoperation in ground-based settings, hot plate precipitation measuringsystem 900 may rest on stand 901, roof top 902 or directly on theearth's surface 121. Alternatively, hot plate precipitation measuringsystem 900 could be lifted to different altitudes in air-borne setting903 by balloon 904 or other air-borne device. It should be noted thatdepending on atmospheric conditions at the time of measurement, stepsmay have to be taken to stabilize the balloon 904 or other air-bornedevice during measurement.

The above-described elements can be comprised of instructions that arestored on storage media. The instructions can be retrieved and executedby the processors. Some examples of instructions are software, programcode, and firmware. Some examples of storage media are memory devices,tape, disks, integrated circuits, and servers. The instructions areoperational when executed by the processors to direct the processors tooperate in accord with the invention. The term “processor” refers to asingle processing device or a group of inter-operational processingdevices. Some examples of processors are integrated circuits and logiccircuitry. Those skilled in the art are familiar with instructions,processors, and storage media.

Thus, it is apparent that there has been described, a hot plateprecipitation measuring system for measuring precipitation rates, thatfully satisfies the objects, aims, and advantages set forth above. Whilethe present hot plate precipitation measuring system has been describedin conjunction with specific embodiments thereof, it is evident thatmany alternatives, modifications, and variations can be devised by thoseskilled in the art in light of the foregoing description. Accordingly,this description is intended to embrace all such alternatives,modifications and variations as fall within the spirit and scope of theappended claims.

What is claimed is:
 1. A precipitation measuring system comprising: afirst sensor configured to maintain a first pair of plates at a firstsubstantially constant temperature; a second sensor configured tomaintain a second pair of plates at a second substantially constanttemperature; and a processor configured to distinguish between a blowingprecipitation event and a falling precipitation event responsive to thefirst sensor maintaining the first pair of plates at the firstsubstantially constant temperature and the second sensor maintaining thesecond pair of plates at the second substantially constant temperature.2. The precipitation measuring system of claim 1 wherein the firstsensor and the second sensor are positioned at different elevations. 3.The precipitation measuring system of claim 2 wherein the processor isconfigured to determine a first precipitation rate responsive to thefirst sensor maintaining the first pair of plates at the firstsubstantially constant temperature and determine a second precipitationrate responsive to the second sensor maintaining the second pair ofplates at the second substantially constant temperature.
 4. Theprecipitation measuring system of claim 3 wherein the processor isconfigured to adjust the first substantially constant temperatureresponsive to the first precipitation rate and to adjust the secondsubstantially constant temperature responsive to the secondprecipitation rate.
 5. The precipitation measuring system of claim 2wherein maintaining the first pair of plates at the first substantiallyconstant temperature indicates a first difference in power consumptionbetween the first pair of plates, wherein maintaining the second pair ofplates at the second substantially constant temperature indicates asecond difference in power consumption between the second pair ofplates, and wherein the processor is configured to determine a firstprecipitation rate responsive to the first difference in powerconsumption, determine a second precipitation rate responsive to thesecond difference in power consumption, and distinguish between theblowing precipitation event and the falling precipitation eventresponsive to the first precipitation rate and the second precipitationrate.
 6. The precipitation measuring system of claim 1 wherein the firstsensor is configured to determine atmospheric temperature and whereinthe processor is configured to determine wind speed responsive to theatmospheric temperature and maintaining one of the first pair of platesat the first substantially constant temperature.
 7. The precipitationmeasuring system of claim 1 wherein the second sensor is configured todetermine atmospheric temperature and wherein the processor isconfigured to determine wind speed responsive to the atmospherictemperature and maintaining one of the second pair of plates at thesecond substantially constant temperature.
 8. The precipitationmeasuring system of claim 1 wherein the first sensor is configured toturn on during the precipitation event and turn off after theprecipitation event.
 9. The precipitation measuring system of claim 1wherein the second sensor is configured to turn on during theprecipitation event and turn off after the precipitation event.
 10. Theprecipitation measuring system of claim 1 wherein a first one of thefirst pair of plates is positioned to protect a second one of the firstpair of plates from precipitation and a first one of the second pair ofplates is positioned to protect a second one of the second pair ofplates from the precipitation.
 11. A method of distinguishing between ablowing precipitation event and a falling precipitation event, themethod comprising: in a first sensor, maintaining a first pair of platesat a first substantially constant temperature; in a second sensor,maintaining a second pair of plates at a second substantially constanttemperature; and distinguishing between the blowing precipitation eventand the falling precipitation event responsive to the first sensormaintaining the first pair of plates at the first substantially constanttemperature and the second sensor maintaining the second pair of platesat the second substantially constant temperature.
 12. The method ofclaim 11 further comprising positioning the first sensor and the secondsensor at different elevations.
 13. The method of claim 12 furthercomprising determining a first precipitation rate responsive to thefirst sensor maintaining the first pair of plates at the firstsubstantially constant temperature and determining a secondprecipitation rate responsive to the second sensor maintaining thesecond pair of plates at the second substantially constant temperature.14. The method of claim 13 further comprising adjusting the firstsubstantially constant temperature responsive to the first precipitationrate and adjusting the second substantially constant temperatureresponsive to the second precipitation rate.
 15. The method of claim 12wherein maintaining the first pair of plates at the first substantiallyconstant temperature indicates a first difference in power consumptionbetween the first pair of plates, wherein maintaining the second pair ofplates at the second substantially constant temperature indicates asecond difference in power consumption between the second pair ofplates, and wherein distinguishing between the blowing precipitationevent and the falling precipitation event comprises determining a firstprecipitation rate responsive to the first difference in powerconsumption, determining a second precipitation rate responsive to thesecond difference in power consumption, and distinguishing between theblowing precipitation event and the falling precipitation eventresponsive to the first precipitation rate and the second precipitationrate.
 16. The method of claim 11 further comprising determiningatmospheric temperature and determining wind speed responsive to theatmospheric temperature and maintaining one of the first pair of platesat the first substantially constant temperature.
 17. The method of claim11 further comprising determining atmospheric temperature anddetermining wind speed responsive to the atmospheric temperature andmaintaining one of the second pair of plates at the second substantiallyconstant temperature.
 18. The method of claim 11 further comprising, inthe first sensor, turning on responsive to the precipitation event andturning off after the precipitation event.
 19. The method of claim 11further comprising, in the second sensor, turning on responsive to theprecipitation event and turning off after the precipitation event. 20.The method of claim 11 wherein a first one of the first pair of platesis positioned to protect a second one of the first pair of plates fromprecipitation and a first one of the second pair of plates is positionedto protect a second one of the second pair of plates from theprecipitation.
 21. A product for a precipitation measuring systemcomprising a processor, a first sensor configured to maintain a firstpair of plates at a first substantially constant temperature, and asecond sensor configured to maintain a second pair of plates at a secondsubstantially constant temperature, the product comprising: processinginstructions configured to direct the processor to distinguish between ablowing precipitation event and a falling precipitation event responsiveto the first sensor maintaining the first pair of plates at the firstsubstantially constant temperature and the second sensor maintaining thesecond pair of plates at the second substantially constant temperature;and a storage medium configured to store the processing instructions.22. The product of claim 21 wherein the first sensor and the secondsensor are positioned at different elevations.
 23. The product of claim22 wherein the processing instructions are configured to direct theprocessor to determine a first precipitation rate responsive to thefirst sensor maintaining the first pair of plates at the firstsubstantially constant temperature and determine a second precipitationrate responsive to the second sensor maintaining the second pair ofplates at the second substantially constant temperature.
 24. The productof claim 23 wherein the processing instructions are configured to directthe processor to adjust the first substantially constant temperatureresponsive to the first precipitation rate and to adjust the secondsubstantially constant temperature responsive to the secondprecipitation rate.
 25. The product of claim 22 wherein maintaining thefirst pair of plates at the first substantially constant temperatureindicates a first difference in power consumption between the first pairof plates, wherein maintaining the second pair of plates at the secondsubstantially constant temperature indicates a second difference inpower consumption between the second pair of plates, and wherein theprocessing instructions are configured to direct the processor todetermine a first precipitation rate responsive to the first differencein power consumption, determine a second precipitation rate responsiveto the second difference in power consumption, and distinguish betweenthe blowing precipitation event and the falling precipitation eventresponsive to the first precipitation rate and the second precipitationrate.
 26. The product of claim 21 wherein the first sensor is configuredto determine atmospheric temperature and wherein the processinginstructions are configured to direct the processor to determine windspeed responsive to the atmospheric temperature and maintaining one ofthe first pair of plates at the first substantially constanttemperature.
 27. The product of claim 21 wherein the second sensor isconfigured to determine atmospheric temperature and wherein theprocessing instructions are configured to direct the processor todetermine wind speed responsive to the atmospheric temperature andmaintaining one of the second pair of plates at the second substantiallyconstant temperature.